Simultaneous measurement of X-ray diffraction patterns and differential temperature curves is an excellent method to eliminate the disadvantages in common DSC analysis. Problems in DSC analysis of polymers include phenomena such as multiple melting and fractionated crystallization. By simultaneous registration of X-ray diffraction patterns the melting and crystallization peaks can be assigned to different phases in multiphase materials. A sample holder was developed which serves the requirements for simultaneous measurement of X-ray diagrams and differential temperature curves. The necessity for the development of the system is shown as well as details of the sample holder and test measurements on polyamides.